Device for controlling the supply of combustion air to a combustion chamber

ABSTRACT

The invention relates to a device for controlling the supply of combustion air to a combustion chamber for solid fuel, the device including a housing having a chamber and having a first end and a second end, a piston arrangement being movable arranged inside the chamber between a first position and a second position, the piston arrangement including a gasket arrangement, an adjustable valve arrangement for providing a fluid communication between the chamber and the exterior of the chamber and being configured for providing a flow of a gas to the chamber, and an elastic force inducing arrangement. The piston arrangement is configured for being moved towards the first end of the housing to the first position, thereby forcing gas inside the chamber out of the chamber through an outlet, and the elastic force inducing arrangement is connected to the piston arrangement and is configured for forcing the piston arrangement from the first position towards the second position. The adjustable valve arrangement is configured for providing gas to the chamber during the movement of the piston arrangement from the first position towards the second position, and the elastic force inducing arrangement is arranged exterior to the chamber. The invention moreover relates to a burning stove or fireplace including such a device.

CROSS REFERENCE TO RELATED APPLICATION

This application is related to and claims the benefit of European Patent Application Number 13181823.9 filed on 27 Aug. 2013, the contents of which are herein incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a device for controlling the supply of combustion air to a combustion chamber for the combustion of solid fuel, and a burning stove or fireplace comprising such a device.

BACKGROUND

The supply of combustion air to a stove or fireplace is often controlled manually. However, it is also known to control the supply of combustion air automatically. Such automatic control may, for example, be based on temperature in the combustion chamber. Such known control systems are able to maintain the temperature of the combustion chamber below desired maximum limits. However, such methods of controlling combustion air supply do not secure an air supply being optimum for obtaining a clean and complete combustion of the fuel within the combustion chamber.

Another method for controlling the supply of combustion air to a combustion chamber is to use a device for controlling the supply of combustion air to the combustion chamber where the time is substantially the only input or variable for controlling the air supply to the bottom of the combustion chamber. Such a solution is disclosed in WO 2008/046425. This is achieved by delaying the movement of a damper of a furnace towards a closed position so that the supply of air is larger at the beginning of the combustion than it is at the end of the combustion. This is e.g. advantageous in that when solid fuel is burned in a combustion chamber, combustible gases are released from the fuel, but to a higher extent during an initial period than at a later stage of the combustion process.

However, the above solutions have some drawbacks in that the present invention intends to solve. For example, the above solutions suffer for problems in relation to e.g. maintenance and adaption in relation to controlling the supply of combustion air over time. Hence, an object of the present invention may be to provide an improved solution for supplying combustion air to a combustion chamber.

BRIEF SUMMARY

The invention relates to a device for controlling the supply of combustion air to a combustion chamber for solid fuel, said device comprising a housing comprising a chamber and having a first end and a second end, a piston arrangement being movable arranged inside said chamber between a first position and a second position said piston arrangement comprising gasket means, adjustable valve means for providing a fluid communication between said chamber and the exterior of said chamber and being configured for providing a flow of a gas to said chamber, and elastic force inducing means, wherein said piston arrangement is configured for being moved towards the first end of said housing to said first position, thereby forcing gas inside said chamber out of the chamber through an outlet, wherein said elastic force inducing means are connected to said piston arrangement and are configured for forcing said piston arrangement from said first position towards said second position, wherein said adjustable valve means are configured for providing gas to said chamber during said movement of the piston arrangement from said first position towards the second position, and wherein said elastic force inducing means are arranged exterior to said chamber.

It has come to the inventor's knowledge that it may be difficult to foresee the control of air to a combustion chamber over time, e.g. in that residue from the combustion such as e.g. cinder and/or ash may prevent or complicate an automatic control of the air supply. This is e.g. due to that the residue may fall into openings between e.g. a damper of a stove comprising the combustion chamber and the wall of the combustion chamber, and/or the device may be exposed to the residues. Moreover, parts of a new stove may slightly change form and/or position over time due to the large temperature differences that the stove is exposed to, and this may demand more or less force over the lifetime of the stove to sufficiently adjust the air supply over time by the device. This may result in a varying friction over time between different movable parts operated by the device, and this may call for an adjustment or maintenance of the device. Therefore, there may e.g. be a need for accessing the force inducing means over time when the stove has been used for an amount of time so as to e.g. exchange the force inducing means.

Additionally, it may be advantageous to use a plurality of devices according to the present invention for air supply to different parts/locations of a combustion chamber, but this may however call for devices with different characteristics so that they are adapted to the specific location of air supply.

In the device according to the invention, the flexible force inducing means are arranged outside the chamber so that a more easy exchange of and access to the force inducing means is facilitated.

Moreover, a stronger spring in combination with the adjustable valve means may help to provide a first time of movement of the piston arrangement between the first and second positions whereas another spring or a piece of rubber may be more suitable for controlling the air supply at another location.

It is generally understood that the adjustable valve means may also be referred to as adjustable valve and/or adjustable valve arrangement.

It is moreover generally to be understood that the gasket means may be referred to as a gasket arrangement and/or one or more gaskets.

The device is hence advantageous for use in a plurality of different scenarios and usages in that it facilitates easy adaption and maintenance over time.

Moreover, the external force inducing means has shown to be advantageous in that a more reliable device is provided if a powerful/strong spring is used compared to if a spring with the same spring properties is arranged inside the chamber.

It is to be understood that the adjustable valve means are adjustable so as to provide a varying flow of air to the chamber according to the setting of the valve means. An adjustment of the valve means may hence e.g. change the size of an opening in the valve means. The gas provided to the chamber of the housing by the valve means is preferably air/gas surrounding the device.

The elastic force inducing means has shown to provide a reliable and space saving solution where an easy exchange of the force inducing means is facilitated. The elastic force inducing means preferably comprises a body or device that recovers its original shape when released after being compressed, stretched or in another way distorted.

It is generally understood that the elastic force inducing means may also be referred to as elastic force inducing arrangement or elastic force inducer.

In aspects of the invention, said elastic force inducing means comprises an elastic material, such as a spring, which is configured for being loaded with potential energy during the movement of the piston towards the first position, and wherein said potential energy provides a force on the piston arrangement so as to force the piston arrangement from the first position towards the second position.

Alternatively, the elastic force inducing means may also comprise rubber or any other suitable means. The elastic force inducing means provides the possibility of establishing a very space saving and reliable device that can be arranged in or at the heating stove, fireplace or the like, e.g. so that the device is fixed to the stove, fireplace or the like and so that it can control a damper of the stove, fireplace or the like. The device(s) may e.g. be arranged below the combustion chamber and be attached to a mounting of the stove or fireplace.

In aspects of the invention, said outlet of the device is provided by a one way valve in said device.

A one way valve provides a cost efficient and yet simple and effective way of providing a rapid outlet of gas from the chamber through the outlet when the piston arrangement is moved towards the first position. The one way valve hence provides the outlet during the movement of the piston arrangement during the movement of the arrangement towards the first position, but prevents an air flow through/by means of the one way valve when the piston arrangement is moved towards the second position by means of the elastic force inducing means.

In advantageous aspects of the invention, said gasket means provides said one way valve by means of a substantially annular gasket configured as a one way valve so as to allow the gas of said chamber to flow between the inner surface of the wall of the housing and the gasket means to the exterior of said chamber during the movement of the piston arrangement towards the first position so that the gas inside said chamber is forced out of the chamber through the outlet.

Thus, the gasket means allow a flow of air from the chamber to the exterior of the chamber when the piston arrangement is moved towards the first position, and the gasket means are moreover configured for preventing a flow of air from the chamber to the exterior of the chamber between the housing wall and the gasket means when the piston arrangement is moved towards the second position by means of the force inducing means. This has shown to provide a simple and cost efficient solution for providing the outlet through which the air is forced when the piston is moved to the first position.

It is however understood that the outlet for the air when the piston arrangement is moved towards the first position may be provided by any other suitable valve means in other aspects of the invention. However, it is preferred that the device comprises a one way valve solution. Another example may be a one way valve arranged in the piston arrangement.

In aspects of the invention, said piston arrangement comprises a rod extending in a direction away from said chamber, and wherein said elastic force inducing means comprise a spring extending around said rod between said housing and a free end of said rod.

The rod provides an advantageous control of both the piston arrangement and the spring. The spring is hence guided by the rod so when the piston arrangement is pushed towards the first position, the spring may be compressed to store potential energy for the subsequent movement of the piston arrangement back to the second position.

Thus, in preferred aspects of the invention, the force inducing means is a coil spring, but in other aspects, the force inducing means may comprise any other suitable elastic part for storing potential energy which is used to move the piston arrangement back to the second position.

In advantageous aspects of the invention, said spring is retained around said rod by means of a retaining part connected to said rod, preferably at the free end at said rod, and wherein said retaining part is releasable connected to said rod by means of locking means, thereby allowing an easy exchange of said flexible force inducing means.

The locking means may comprise a thread, a latch/notch arrangement or any other suitable locking arrangement. The locking means is preferably integrated in the rod and the retaining part so that there is no need to use screws, a clip solution or the like, however, in aspects, the locking means may comprise screws, a further clip for connecting the rod and the retaining means and/or the like.

This aspect provides the possibility of an easy exchange of the spring so that the device can be adapted over time dependent on the usage of the device and/or if the spring is worn or need exchange due to e.g. larger or less friction as described above.

In aspects of the invention, said locking means are configured for allowing a relative linear movement of said retaining part along the rod towards the housing when the retaining part is connected to the rod, preferably so that the retaining part can pivot on the rod, and

wherein said spring is configured for pressing the connection part in a direction towards the free end of the rod.

The pivoting feature provides a device which is more stable to forces acting on the free end of the rod to move the piston arrangement towards the first position when the forces are not precisely parallel to the movement direction rod. The retaining part may hence be partly displaced on the rod toward the chamber and thus be retained on the rod with an angle in relation to the longitudinal direction of the rod. The retaining part may be a ring/annular formed part or a part having any other suitable form.

In preferred aspects of the invention, said adjustable valve means are arranged in a wall of the housing at the first end of the housing, preferably in a first end wall of the housing, and wherein said force inducing means are arranged at the opposite end of the device.

This provides a device that is easy and cost efficient to produce while at the same time providing a reliable supply of gas to the chamber by the valve means. Additionally, the device hereby provides an advantage when installing it in a stove or the like in that the valve means are easy accessible from e.g. the front side of the stove or the like, while the movement of the piston arrangement towards the second position may be provided by pulling a handle. Alternatively, the valve means may be arranged at another location, e.g. in the piston arrangement.

Generally, the valve means may be any suitable valve arrangement providing an adjustable valve.

However, in embodiments of the invention, said valve means may comprise an opening with a conical wall and an adjustable part such as a screw extending into said opening, wherein the flow of gas to said chamber provided by said valve means is configured for flowing between the adjustable part and the conical wall from the exterior of the chamber.

The conical wall provides the advantage that the flow of air may be adjusted simply by moving the adjustable part in the opening. If it is a screw, the thread of the screw may engage the conical wall by turning the screw around its longitudinal direction so that the screw is moved relative to the wall. Hence, by moving the adjustable part towards the narrower end of the conical wall, the flow of air is reduced, and by moving it towards the wider end of the conical wall, the flow of air is increased. Thus, the valve may be adjusted and thereby set to control the time that it takes for moving the piston arrangement towards the second position.

In preferred aspects of the invention, wherein the movement of the piston arrangement from the first position to the second position is adjustable by the valve means, and

wherein the valve means are configured to be adjusted to a first setting where the movement takes below 20 min, and a second setting of said valve means so that the movement takes more than 20 min. such as at least 30 min. for example at least 60 min, e.g. at least 120 min.

This provides a solution where a plurality of devices may be used during substantially the whole combustion process in the combustion chamber so that a first device set to the first setting, e.g. 10 min. regulates a first valve/damper of the stove, fireplace or the like to gradually reduce the supply of combustion air during the initial period of the combustion process, preferably from the bottom of the chamber, and a second device may hence be used for controlling another valve/damper of the stove, fireplace so that the flow of air to the combustion chamber is increased or decreased later in the combustion process. The piston arrangements of the different devices may hence be set to the first position at the initiation of the combustion and need no further control until e.g. reloading the combustion chamber with new solid fuel.

Generally, the first and second positions are preferably defined by first and second end walls of the housing, but may in further aspects also be defined by other parts of the housing.

In preferred aspects of the invention, said device is made from a heat resistant material so that the device is mechanically resistant to temperatures above 50° C. such as above 70° C., preferably above 90° C., and wherein at least said housing and preferably also said piston arrangement is made from a heat resistant polymer such as polycarbonat and/or a Polyoxymethylene (POM).

This provides a solution where the device may be arranged relatively close to the combustion chamber and a damper of the stove, thereby providing e.g. a simple and more space saving solution. Moreover, the mentioned polymers have shown to be especially advantageous for the housing and the piston arrangement in that it is high strength materials with a low coefficient of friction which provides that the piston arrangement may abut and slide easily along the inner surface of the polymer housing.

In aspects of the invention, the length (L1) of the housing (2) is be below 300 mm, preferably as below 100 mm, such as around 60 mm, and wherein the length (L1) of said housing (2) is above 20 mm such as above 30 mm, e.g. above 40 mm.

This provides a device which is space saving so that it may be arranged in the stove/fireplace, e.g. below the combustion chamber, and at the same it time provides that the piston arrangement may move over a distance from the first position to the second position that makes it more easy to adjust the valve means so that a desired movement time of the piston arrangement can more easily be set by adjusting the valve means.

In preferred aspects of the invention, the device is suitable for being arranged in a stove, fireplace or the like comprising said combustion chamber, such as below said combustion chamber.

The invention more over relates to a burning stove or fireplace, wherein said burning stove or fireplace comprises a combustion chamber and at least one damper, wherein said device is connected to said damper to control the supply of combustion air said combustion chamber.

The above mentioned device provides several advantages in relation to providing a reliable and adaptive way of controlling the supply of combustion air to the combustion chamber for solid fuel.

In aspects, said burning stove or fireplace comprises at least two of said devices wherein said devices are arranged to control at least two different dampers of the stove or fireplace during the combustion of solid fuel in the combustion chamber, wherein a first of said dampers is configured to be controlled by a first device so as to provide combustion air to the combustion chamber within the first 20 min of said combustion, preferably at the bottom of said combustion chamber, and

wherein a second of said dampers is controlled by a second device so as to be closed for at least the first 20 min of the combustion, and provide air to the combustion chamber at a later time during said combustion.

Due to the configuration of the device according to aspects disclosed in this document, the device is advantageous for use in a plurality of various configurations for providing air to the combustion chamber.

The invention may moreover relate to a method of controlling the supply of air to a combustion chamber according to the above aspects.

FIGURES

Exemplary embodiments of the invention will be described in more detail in the following with reference to the figures, of which:

FIGS. 1-1 a illustrate a cross section of a device according to embodiments of the invention,

FIGS. 2 a-2 c illustrates the operation of a device as disclosed in FIG. 1,

FIG. 3 illustrates a further embodiment of the invention,

FIGS. 4 a-5 illustrates further embodiments of a device according to aspects of the invention,

FIG. 6 illustrates an embodiment of a stove or fireplace according to embodiments of the invention,

FIG. 7 illustrates a further embodiment of supply of combustion air to the combustion chamber,

FIG. 8 illustrates a heating stove or fireplace comprising a plurality of devices for controlling the supply of combustion air, and

FIGS. 9-9 a illustrate dimensions of a device according to embodiments of the invention.

DETAILED DESCRIPTION

FIG. 1 discloses a preferred embodiment of a device according to the present invention in its initial “resting” position.

The device comprises a housing 2 with a chamber 3, the housing 2 is has a tubular wall 15 a first end E1 and a second end E2. The first end is defined by a first end wall 14, and the second end is defined by a second end wall 16.

The first end wall 14 comprises adjustable valve means 4 configured for providing a fluid communication between the chamber 3 and the exterior 5 of the housing 2 so as to provide a controlled flow of a gas to said chamber 3 from the exterior of the chamber.

Moreover, the device comprises a piston arrangement 6 being movable arranged inside the chamber 3 so that it can be moved linear between a first position P1 defined by the first end wall 14, and a second position P2 defined by the second end wall 16 in the longitudinal direction of the housing.

The piston arrangement comprises annular or circular gasket means 7 abutting the inner surface 8 of the tubular wall 15 of the housing 2. The gasket means 7 are arranged so that they work like a one way valve providing a gas outlet 19 between the inner surface of the housing wall 15 and the gasket means 7.

The piston arrangement 6 comprises a piston head 17 and is configured for being moved in a linear movement towards the first end El of the housing 2 to the first position P1. This movement forces gas inside the chamber 6 out of the chamber through an outlet 19. In this case, the gasket means 7 acts as a one way valve and are used as the outlet 19 so that the air is forced between the gasket means 7 and the inner surface 8 of the tubular wall 15 during the movement to the first position P1 and out of the chamber 3.

The device moreover comprises force inducing means 9 arranged exterior to the chamber 6. The force inducing means 9 are in the present embodiment a spring extending around a rod 10 of the piston arrangement. The spring 9 is arranged between a retaining part 12 and the second end wall 16 of the housing so that the spring is compressed when moving the piston arrangement towards the first position P1 by pushing on the rod 10 to provide a relative movement between the housing and the piston arrangement. This movement will load the spring with potential energy, and the spring 9 will hence try to recover its original shape, thereby trying to push the piston arrangement 6 away from the first position P1 towards the second position.

The gasket means 7 are arranged to be air tight in a way so that the air cannot be sucked into the chamber 3 between the gasket means 7 and the wall 8 due to the one way valve configuration. Hence, the valve means 4 in the end wall 14 will be the only way of supplying air to the chamber 3 so that the piston arrangement 6 can be moved towards the second position P2 by means of the spring 9. The valve means 4 may hence slow down the movement of the piston arrangement 6 towards the second position P2 according to the setting of the valve means 4.

Thus, by adjusting the valve means 4, an opening in the valve means is gradually decreased or increased thereby providing the possibility of adjusting the speed with which the piston arrangement 6 moves to its initial position/second position due to the force applied by the force inducing means 9 (e.g. a spring). Thus, the valve 4 provides the possibility of controlling the time with which the piston arrangement 6 is moved from the first position P1 to the second position P2.

The retaining part 12 is arranged to be releasable connected to the rod 10 so that the spring can easily be changed to a different kind of spring or a new spring if the previous is broken.

The releasable connection is provided by locking means/arrangement 13.

The rod 10 is arranged to extend in the movement direction MD of the piston arrangement 6 and into the interior of the housing 2 through a center opening in the end wall 16. Here it is connected to the piston head 17, and the piston head comprises the gasket means which abuts the inner surface of the tubular wall. The chamber 3 is hence arranged between the piston head 17 and the first end wall 14.

It is to be understood that the device 1 is intended for controlling the supply of combustion air to a combustion chamber of a burning stove, fireplace or the like in connection with burning solid fuel such as wood, wood pellets, bales of straw, timber refuse, coal, coke, briquettes, etc. Hence it is preferred if the parts of the device 1 are made of heat resistant material in that it may often be placed near the combustion chamber. The housing 2, piston arrangement 6 and/or the like of the device 1 may hence be made of a heat resistant polymer such as e.g. polycarbonat or Polyoxymethylene (POM) or any other suitable heat resistant material. Such materials may be easy to manipulate so that a cost efficient device may be e.g. injection molded or the like. Alternatively, the housing 2 and/or the piston arrangement 6 may be made of a metal such as brass, steel, iron or another suitable alloy. By the term heat resistance is to be understood that the device 1 is mechanically resistant to temperatures above 50° such as above 70°, e.g. above 90°.

The device may hence be produced by pulling e free end 11 of the rod through the central opening 18 in the wall 16, and then arranging the piston head in the chamber 3 of the housing 2. Then the wall 16 is fixed to the housing by a latch/notch configuration, glue, screws and/or any other suitable attachment means. Moreover, the spring 9 is pulled over the rod and retained in this position by fixing the retaining means onto the rod 11 by the locking arrangement 13. The arranging of the spring 9 on the rod 10 may in aspects be done before arranging the piston head in the chamber of the housing and attaching the end wall 16 to the housing.

Since the gasket means 7 provides a connection which is substantially airtight in a way so that no air can pass the piston when the piston is moved towards the second position P2, the only supply of air to the chamber 3 during this movement is provided by the valve 4. Hence, the movement of the piston arrangement 6 towards the second position P2 will only be allowed due to the intake of air through the valve 4. This intake of air is provided by the force of the spring 9 which is trying to press the piston arrangement towards the second position P2. Hence, if the valve is substantially closed, the spring may establish a small vacuum in the chamber 3.

FIG. 1 a illustrates a preferred embodiment of the valve means 4. The valve means 4 comprises a screw 20 and a conical wall 21 in the end wall 14 extending into the compartment 3. Alternatively, the conical wall may extend outwards from the housing (not illustrated). The conical wall 21 hence provides an opening into the chamber 3. The conical shape of the wall 14 provides a gasket feature so that the opening in the wall 14 is given by how far the screw 20 is screwed into the opening. The longer the screw 20 extends into the opening, the more the valve is sealed and the less air is provided into the chamber. The air hence enters into the chamber 3 between the thread (not illustrated) of the screw 20, and the conical wall. It may be preferred that the screw is made of metal with a head comprising a recess for receiving a tool to turn the screw. Alternatively the screw may be a thumbscrew. The screw 20 may hence cut into the conical wall which may be made of a polymer as described above, to provide a thread in the wall.

FIG. 2 a-2 c illustrates the operation of the device 1 according to FIG. 1.

In FIG. 2 a, the piston arrangement 6 is pushed towards the first position P1 by a force F2 acting on the rod 10 so that the rod 10 and the piston head 17 is moved into the compartment of the housing 2. As illustrated by the dashed arrows 25, this forces air from the chamber 3 out of the chamber between the gasket 7 and the wall 15. The force F2 may be provided manually by a pushing or pulling action, or automatically by a loading mechanism which pushes the piston arrangement towards the second position during e.g. opening of a door in the stove to provide new fuel to the combustion chamber.

As illustrated, the gasket means 7 may comprise a flexible and preferably also elastic annular ring or plate made from a material such as rubber, a silicon material or the like. The gasket means 7 comprises an elastic annular flap 7 a extending in a direction away from the first end E1 and is configured so that at least a part of the flap 7 a abuts the inner surface of the tubular wall 15. When pushing the piston arrangement to the first position, the flap allows air to pass between the wall 15 and the flap 7 a, thereby providing the outlet 19. However, the flap 7 a is configured so that a movement of the piston arrangement 6 towards the second end E2 of the housing 2 will push or at least keep the flap against the wall 15 thereby providing a substantially airtight connection between the wall 15 and the annular flap 7 a so that no air can pass between the wall 15 and the flap 7 a into the chamber 3.

The gasket means 7 may e.g. be fixed to the piston arrangement 6 by glue, a clamping part 100 for clamping the gasket means 7 between the piston head 17 and the part 100 and/or by any other suitable means.

In FIG. 2 b the piston arrangement is moved all the way to the first position P1 and is now ready to move towards the second position due to a combination of the air intake of by the valve 4 and the force F1 provided by the spring 9.

In FIG. 2 c, the spring 9 forces the piston arrangement towards the second position due to the force F1 provided by the spring 9. The air intake (illustrated by dashed arrow 26) into the chamber to during the movement of the piston arrangement 6 is provided through the valve 4. Hence, the adjustment/setting of the valve determines the speed of movement of the piston arrangement 6. When the piston head reaches the inner surface of the second wall 16, the piston is retained in this initial position as illustrated in FIG. 2.

FIG. 3 illustrates the retaining means 12. In advantageous embodiments, the retaining part 12 is configured so that a certain movement away from the free end 11 of the rod 10 is possible by a pressure on the surface 30 of the retaining part facing away from the housing 2 (not illustrated in this fig.) this slightly compresses the spring 9 so that the retaining part is pushed back towards the free end 11 of the rod when the force F2 is removed. Moreover, FIG. 3 illustrates a further embodiment of the rod 10 where the rod 10 is substantially shaped as a plus (+)

FIGS. 4 a-4 c illustrates an embodiment of the retaining part 12 and the free end 11 of the rod 10. The retaining means comprises an annular ring 40 with a pair of protrusions 41 extending into the opening 42 of the ring 40. The opening 42 is configured so that the end of the rod 10 can enter the opening 42, and so that the protrusions 41 extend into recess 44 along the rod 10. The Ring is then turned relative to the rod 10 around the centre axis of the rod 10 until the protrusion 41 and are then pressed against the lower side of a stop part 46 of the rod 10. The spring 9 (not illustrated in this fig) presses the protrusions 41 against the lower side of the stop part 46 so that the retaining means 12 are retained on the rod 10 and thus retains the spring 9 on the rod between the wall 16 and the retaining part 12. The retaining part 12 can thus move on the rod 10 towards the housing 2 by compressing the spring. Moreover, the rod preferably comprises means, in the form of e.g. a protrusion 45, for preventing the retaining part 12 from rotating relative to the rod to a release position where the retaining part 12 is released from the rod 10. The retaining means may hence need to be moved relative to the rod towards the housing 2 before allowing a rotation of the retaining part to a release position so that the retaining part and hence also the spring 9 can be removed from the rod. FIG. 4 c illustrates the rod seen from the free end 11 where the retaining part 12 is connected to the rod 10.

FIG. 5 illustrates an embodiment where the flexible force inducing means 9 is an elastic part in the form of a spring, rubber or the like arranged external to the rod 10 and are connected to the rod and a part 50 of the stove. Hence, the rod 10 may be pressed into the chamber 3 of the housing 2 towards the first position as illustrated in FIG. 1, thereby stretching the spring, rubber material or the like, hence, the elastic force inducing means 9 tries to pull the rod 10 back to the second position as illustrated in FIG. 1, and the valve 4 hence controls the flow of air into the chamber in the housing.

FIG. 6 illustrates an embodiment of the invention where the device 1 is installed in a wood stove, fire place or the like 59. The wood stove, fire place or the like 59 may in this document be referred to as just “stove”.

The stove 59 comprises a combustion chamber 60 for containing the solid fuel to be burned to provide heat. The bottom 70 of the combustion chamber 60 comprises an opening 71 for supplying air to the combustion chamber 60. The stove 59 moreover comprises a damper 80 for controlling the supply of air to the bottom of the combustion chamber. By moving the damper relative to the opening 71, the opening for supply of combustion air is decreased or increased dependent on the position of the damper 80.

The damper 80 may e.g. be a plate as illustrated or another suitable type of adjustable part for controlling the flow of air to the combustion chamber 60.

By pulling the handle 82, which is connected to the damper 80, away from the stove 59, the opening 81 of the damper 80 is set to a position opposite to the opening 71, thereby providing the maximum amount of combustion air to the combustion chamber 60. The device 1 is moreover connected to the damper 80 so that by pulling the handle 82, the piston arrangement 6 is moved to the first position P1 as illustrated in the previous figures and as described above. The spring 9 now forces the piston arrangement 6 back towards the first position P1, thereby also displacing the damper 80 so that the flow of air is gradually decreased according to the setting of the adjustable valve 4 of the device 1. It is understood that the damper 80 preferably is a damper arranged to be moved linear between two positions and may comprise any suitable opening or openings 81 for controlling the supply of combustion air to the combustion chamber 60.

The device 1 is hence connected to a frame structure/mounting 63 of the stove 59 so that the housing 2 is kept in a fixed position.

The upper opening 62 in the combustion chamber is an outlet for the gases occurring during the combustion so that such gasses can leave the combustion chamber. The opening 62 may hence be configured for being connected to e.g. a chimney.

Even though FIG. 6 discloses a stove 59 with one device 1, it is understood that the stove 59 may comprise more than one such as two, three or even more devices 1. These devices may control different dampers of the stove 59 so that the supply of air to the combustion chamber is provided to different parts of the combustion chamber at different times during the combustion.

This is illustrated in FIG. 7. The damper 80 is configured so that when the piston means are moved towards the first position p1, the damper 80 will cover the entire opening 111 in the wall 110 to the combustion chamber 60 so that it is first after a certain amount of time (and movement of the piston arrangement 6 towards the second position P2) that the opening 111 receives combustion air from the outside of the combustion chamber 60. In this case due to that the part 83 of the damper 80 will cover the opening 111 until the opening 81 gets in a position opposite to the opening 111.

FIG. 8 illustrates an embodiment of a stove comprising three dampers 80 and three devices 1 for controlling the supply of combustion air to the chamber 60 through an opening 71 in the bottom of the combustion chamber and two openings 111 in the wall 110 enclosing the chamber 60. The devices 1 hence individually controls the different dampers 80 arranged at different locations to provide combustion air at to different locations in the combustion chamber.

It is understood that the devices 1 in embodiments (not illustrated) of the invention may be arranged e.g. at the bottom of the stove/fireplace or the like and the piston arrangement 6 may hence be connected to a connection part (not illustrated) connected the dampers at the different locations in the furnace 59 so that all the devices may be set from the bottom by e.g. a handle.

Embodiments of the dimensions of the device 1 may be as described in relation to FIG. 9. The length L1 of the housing 2 may be below 200 mm, such as below 100, such as around 60 mm. However it is moreover preferred that the housing longer than 20 mm such as longer than 40 mm to provide sufficient space for the piston stroke between the positions P1, P2 (see FIG. 1), and thereby sufficient adjustment possibilities by the valve means 4 so that the same device 1 may be used for controlling different air supplies as disclosed in relation to e.g. FIGS. 6-8.

The total length L2 of the device 1 in an expanded position, i.e. when the piston arrangement 6 is moved all the way back to the second position P2 by the force inducing means 9, may be around 400 mm such as 200 mm, for example around 120 mm from the free end of the rod to the end wall 14.

E.g. due to the above dimensions, the valve means 4 may be adjusted to a first setting where the movement of the piston arrangement 6 from the first position P1 to the second position P2 (see FIG. 1) due to combination of the spring and the setting of the valve means 4 takes below 20 min, and a second setting of the valve means 4 so that the movement takes more than 20 min. such as at least 30 min. for example at least 60 min, e.g. at least 120 min.

The diameter D1 of the housing 2 may be no more than 100 mm such as no more than 80 mm, e.g. no more than 60 mm such as around 40 mm. as illustrated in FIG. 9 a. FIG. 7 a discloses an embodiment of the device seen from the end 11 of the rod 10.

The device 1 moreover comprises a ring formed connection part 90 configured for connecting to e.g. a frame structure/mounting 63 as described above. The connection part 90 may moreover comprise one or more connection means such as holes (91) for screws or other fastening means, a latch/notch solution or the like or the like so that the device 1 can be fixed to the frame structure/mounting. The ring formed connection part 90 is preferably arranged substantially at the second end E2 of the housing and may be configured so as to provide a force towards a frame structure/mounting 63 of the stove or the like when the piston arrangement is forced towards the first position P1 by e.g. pulling a handle.

It is generally understood that the invention is not limited to the above examples but may be combined in a multitude of varieties as specified in the claims. Additionally, it is understood that different aspects of the figures and/or the description above may be combined to obtain further embodiments. For example, the valve means 4, the gasket means 7 configured as a one way valve, the force inducing means and/or the like may in other embodiments be substituted by other suitable solutions. For example, the valve means 4 may comprise another valve solution and may in further embodiments be arranged at another location such as e.g. in the piston arrangement, e.g. in the piston head. The gasket means 7 configured as a one way valve may in embodiments also be arranged in housing piston head so that the gasket means 7 are substantially air tight in both movement direction of the piston arrangement. The force inducing means 9 may instead of a spring around the “piston rod” 10 be an elastic material or part such as rubber, a compressible gas piston or the like which is configured for recovering to its initial position after deformation. 

1. A device for controlling the supply of combustion air to a combustion chamber for solid fuel, said device comprising a housing comprising a chamber and having a first end and a second end, a piston arrangement being movable arranged inside said chamber between a first position and a second position, said piston arrangement comprising a gasket arrangement, an adjustable valve arrangement for providing a fluid communication between said chamber and the exterior of said chamber and being configured for providing a flow of a gas to said chamber, and an elastic force inducing arrangement, wherein said piston arrangement is configured for being moved towards the first end of said housing to said first position, thereby forcing gas inside said chamber out of the chamber through an outlet, wherein said elastic force inducing arrangement is connected to said piston arrangement and is configured for forcing said piston arrangement from said first position towards said second position, wherein said adjustable valve arrangement is configured for providing gas to said chamber during said movement of the piston arrangement from said first position towards the second position, and wherein said elastic force inducing arrangement is arranged exterior to said chamber.
 2. A device according to claim 1, wherein said elastic force inducing arrangement comprises an elastic material, such as a spring, which is configured for being loaded with potential energy during the movement of the piston towards the first position, and wherein said potential energy provides a force on the piston arrangement so as to force the piston arrangement from the first position towards the second position.
 3. A device according to claim 1, wherein said outlet is provided by a one way valve of said device.
 4. A device according to claim 3, wherein said gasket arrangement provides said one way valve by means of a substantially annular gasket configured as a one way valve so as to allow the gas of said chamber to flow between the inner surface of the wall of the housing and the gasket arrangement to the exterior of said chamber during the movement of the piston arrangement towards the first position so that the gas inside said chamber is forced out of the chamber through the outlet.
 5. A device according to claim 1, wherein said piston arrangement comprises a rod extending in a direction away from said chamber, and wherein said force inducing arrangement comprises a spring extending around said rod between said housing and a free end of said rod.
 6. A device according to claim 5, wherein said spring is retained around said rod by means of a retaining part connected to said rod, preferably at the free end at said rod, and wherein said retaining part is releasable connected to said rod by means of a locking arrangement, thereby allowing exchange of said flexible force inducing arrangement.
 7. A device according to, claim 6, wherein said locking arrangement is configured for allowing a relative linear movement of said retaining part along the rod towards the housing when the retaining part is connected to the rod, preferably so that the retaining part can pivot on the rod, and wherein said spring is configured for pressing the retaining part in a direction towards the free end of the rod.
 8. A device according to claim 1, wherein said adjustable valve arrangement is arranged in a wall of the housing at the first end of the housing, preferably in a first end wall of the housing, and wherein said force inducing arrangement is arranged at the opposite end of the device.
 9. A device according to claim 1, wherein said valve arrangement comprises an opening with a conical wall and an adjustable part such as a screw extending into said opening, wherein the flow of gas to said chamber provided by said valve arrangement is configured for flowing between the adjustable part and the conical wall from the exterior of the chamber.
 10. A device according to claim 1, wherein the movement of the piston arrangement from the first position to the second position is adjustable by the valve arrangement, and wherein the valve arrangement is configured to be adjusted to a first setting where the movement takes below 20 min, and a second setting of said valve arrangement so that the movement takes more than 20 minutes.
 11. A device according to claim 1, wherein said device is made from a heat resistant material so that the device is mechanically resistant to temperatures above 50° C., and wherein at least said housing and preferably also said piston arrangement is made from a heat resistant polymer such as polycarbonat and/or a Polyoxymethylene.
 12. A device according to claim 1, wherein the length of the housing is be below 300 mm, and wherein the length of said housing is above 20 mm.
 13. A device according to claim 1, wherein the device is suitable for being arranged in a stove, fireplace or the like comprising said combustion chamber.
 14. A burning stove or fireplace, wherein said burning stove or fireplace comprises a device according to claim 1, said burning stove or fireplace comprising a combustion chamber and at least one damper, wherein said device is connected to said damper to control the supply of combustion air to said combustion chamber.
 15. A burning stove or fireplace according to claim 14, wherein said burning stove or fireplace comprises at least two of said devices, and wherein said devices are arranged to control at least two different dampers of the stove or fireplace during the combustion of solid fuel in the combustion chamber., wherein a first of said dampers is configured to be controlled by a first device so as to provide combustion air to the combustion chamber within the first 20 min of said combustion at the bottom of said combustion chamber, and wherein a second of said dampers is controlled by a second device so as to be closed for at least the first 20 min of the combustion, and provide air to the combustion chamber at a later time during said combustion. 